An electronic component has conventionally formed on a substrate.
Here will be described a flat coil as a conventional electronic component with reference to FIG. 9. FIG. 9 is a perspective view of a conventional flat coil. Coil-shaped or helical wiring 2 is formed on substrate 1 including an alumina substrate and is covered with protecting section 3 made of insulating resin. External electrodes 4 are connected to both ends of wiring 2. Such structured flat coil is mounted on a printed circuit board via external electrodes 4. In response to demands for downsizing electronic components, manufacturers makes some more progress on the path to miniaturization; recent technology seeks an ultra-compact structure with a dimension of 0.4 mm×0.2 mm×0.2 mm (the so-called 0402 component), as is shown by X, Y and Z in FIG. 9.
Next will be described obstacles to miniaturization of electronic components with reference to FIG. 10.
FIG. 10 shows the relationship of the dimension of a conventional electronic component, the area (mm2), the weight (mg) and the ratio of the area to the weight. The x-axis represents the dimension of products that gets smaller toward the right: 3216 (3.2 mm×1.6 mm); 20125 (2.0 mm×1.25 mm); 1608 (1.6 mm×0.8 mm); 1005 (1.0 mm×0.5 mm); 0603 (0.6 mm×0.3 mm); and 0402 (0.4 mm×0.2 mm). On the other hand, the y-axis represents the following three: the area of a product (specifically, it shows the total area (mm2) of the six faces that is shown by a graph with a combination of dotted lines and ‘∘’ in FIG. 10); the weight of the product (specifically, it shows the weight (mg) when the product has a density of 1 g/cc that is shown by a graph with a combination of dash-single-dot lines and ‘⋄’); and the ratio of the area to the weight shown by a graph with a combination of solid lines and ‘Δ’). It will be understood that the graph showing the ratio of the area to the weight has a sharp rise as the product is getting smaller. Such an extremely downsized electronic component, since it is mainly made of insulating resin, is susceptible to static electricity. This will be easily understood by an example where a minute plastic powder (of less than 1 mm in diameter) exhibits high adherability under the influence of static electricity.
Compared to the electronic component mainly made of resin, a ceramic-based electronic component, such as a laminated ceramic capacitor, has larger specific gravity ranging from 3 to 10, which protects the component from the influence of static electricity. Similarly, a square chip resistor and the flat coil shown in FIG. 9 have a substrate as a main structure. By virtue of the weight of the substrate, the two components above are less susceptible to the influence of static electricity.
In contrast, resin-based electronic components, because of a small specific gravity of approx. 1, have a lightweight structure. Besides, the shapes of the components have little difference in density and specific gravity in the vertical and the horizontal directions. That is, the smaller the chip size, the more susceptible to the influence of static electricity. The susceptibility to static electricity causes poor handling of each electronic component. Therefore, manufacturers are having difficulties in retrieving a necessary component from a magazine case containing various components.
For example, Japanese Patent Unexamined Publication No. H09-270355 is known as a prior art relating to the present invention.
As for the electronic components having resin as a main component and therefore having a small specific gravity, the smaller the size, the more increase the area of each component. This allows the miniaturized component to increase the tendency of clinging under the influence of static electricity. For example, when the 1005-component and the 0603-component make contact with each face, it is difficult to separate one from the other. In some cases, an excessive force applied to separate them can impair the characteristics or reliability of the components. From this reason, improvement in handleability has been a pending problem.